1. Field of the Invention
The present invention relates to a single-core full-duplex transceiver structure. In particular, the present invention relates to a novel stack-integration package of a light emitter and a photodetector in a high speed, full duplex optical transceiver for fiber communications.
2. Description of the Related Art
Modern optical communications demand large quantity of high-speed photo-detectors and light emitting devices as the essential optical emitting and receiving components. In optical fiber communication links, a transmitter is the electrical to optical (E-O) converter, which is generally comprised of an LD (Laser Diode) or LED (Light Emitting Diode) and a driver IC as a package in a connector form while a receiver is an O-E converter comprising a PD (photodiode) and a signal processing IC packaged also in the same connector form for user friendly applications. An optical fiber that is fitted with a transmitter connector on one end and a compatible receiver connector on the other offers a unidirectional digital optical data communication link in what is called single-core, simplex optical transmission. For bi-directional communication, two unidirectional digital optical data communication links are required, one for each direction. In this configuration, the transmitter and receiver connectors are two separate housings and two separate optical fiber cores are deployed, one for each direction.
However, for cost saving, it is desirable to use a single core of fiber and a single transceiver connector on each end for bi-directional transmission. The present invention is an innovation in the making of such a bi-directional transceiver that allows bi-directional optical data transmission over a single core of fiber using one single transceiver housing on each end.
There are many prior arts related to single-core full-duplex transceiver structure, such as U.S. Pat. Nos. 6,353,491, 6,236,477, 6,188,495, 5,157,760, 6,097,521, 5,967,622, 5,555,334, 5,416,624, 5,408,559, 5,127,075, etc. All these methods are structurally complex involving sophisticated fiber branching (FIG. 1), beam splitting (FIG. 2) or other techniques. FIG. 1 illustrates the fiber branching method disclosed in U.S. Pat. No. 6,157,760, where 1×2 branching fibers are used so that outgoing light from the emitter is guided by the branch fiber into the trunk fiber while incoming light from the fiber goes straight through the trunk fiber onto the photo-detector. FIG. 2 depicts the beam splitting method disclosed in U.S. Pat. No. 6,353,491 where optical a beam splitter is used so that outgoing light from the emitter is reflected by the splitter into the fiber, while incoming light from the fiber is transmitted straight through the splitter onto the photo-detector. These prior arts preclude collocation of the emitter and the photo-detector chips and require sophisticated precision packaging processes, making them difficult and expensive to make and unreliable to use. The present invention provides a simplified packaging method that saves drastically in both space and cost.